Internal combustion engines typically require oxygen, fuel and a sufficient temperature in order to support combustion. The forces released through such combustion are then typically harnessed to perform work, such as powering an automobile.
In general, such systems typically utilize liquid fuels, such as gasoline. These systems incorporate a liquid fuel delivery system to provide adequate quantities of fuel to the situs of combustion. One such fuel delivery system makes use of fuel injection valves that allow a predetermined quantity of fuel to be injected into the combustion chamber. By appropriate control of the fuel injection valve, both the time of injection and the quantity of fuel injected can be controlled.
Many such fuel injection systems are electronically controlled. These systems typically have one or more fuel injection valves that are solenoid controlled. These solenoids are controlled by drive units, which can be controlled by a control unit. The control unit will often control many such drive units (and hence fuel injection valves) based upon information regarding current engine operating parameters and operator commands. Through use of such a system, both the time of injection and the quantity of fuel injected can be carefully controlled and performance of the engine optimized.
There are, however, certain problems associated with such systems. For instance, under certain fault conditions, the fuel injection valve solenoid may remain on or off in an uncontrolled manner. The former condition can result if either the control signal from the control unit faults "on" or if some other fault occurs in the system that holds the solenoid on. The "off" condition can result if the control signal from the control unit faults "off," or if some other fault occurs in the system to uncontrollably deprive the solenoid of operating current.
If the solenoid becomes uncontrollably deprived of operating current, the problem essentially becomes one of maintenance. The operation of the engine in question will likely be impaired, and appropriate maintenance must be provided to ensure optimum performance. If the solenoid faults "on", however, a more dangerous circumstance can arise. In addition to impaired engine performance, an uncontrolled delivery of fuel to the engine can result in a perilous condition that poses risk to both the engine and its physical surroundings.
There therefore exists a need for a fault detect device that can detect when a fuel injection solenoid faults "on" or "off". Such a device should provide some form of fault protection upon detecting that the solenoid has faulted "on" in order to alleviate the risk associated with that particular fault condition. Also, such a device should provide fault data regarding the existence of an "off" fault condition, so that appropriate maintenance can be provided in a timely fashion.